Stationary contact structure for electrical circuit breakers



Jan. 9, 1968 A. LATOUR 26,336

STATIONARY CONTACT STRUCTURE FOR ELECTRICAL CIRCUIT BREAKERS Original Filed Dec. 15, 1961 INVENTOR Andre Lafour bmyaww M AT ORNEYS United States Patent Ofifice Patented Jan. 9, 1968 26,336 STATIONARY CONTACT STRUCTURE FOR ELECTRICAL CIRCUIT BREAKERS Andr Latour, Grenoble, France, assignor to Ets Merlin & Gerin S.A., Grenoble, France Original No. 3,202,781, dated Aug. 24, 1965, Ser. No. 159,614, Dec. 15, 1961. Application for reissue Oct. 10, 1966, Ser. No. 589,180

9 Claims. (Cl. 335-195) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to stationary contacts for electrical circuit breakers and more especially to stationary contacts for high breaking capacity circuit breakers.

In circuit breakers for high breaking capacities, the movable part of the circuit breaker has considerable inertia due to its bulky structure.

To avoid the bruising of the stationary sparking contact and its progressive destruction, under the influence of the shocks imparted by the movable contact, it has been proposed to provide the stationary terminal with a movable contact at the end of its circuit closing movement is which can be a main or/and arcing contact bias means whereby electrical connection means are provided between the movable member and the stationary terminal. This stationary contact structure has given good results in absorbing the shock of the movable contact of the circuit breaker, but is unsatisfactory in the case of a circuit breaker having a very high breaking capacity where the spring bias is unable to absorb the total of the kinetic energy of the movable contacts, and cannot eliminate bouncing of the same.

It is an object of the present invention to provide an improved stationary contact structure in which the dangers of bruising and bouncing of the contacts are eliminated or reduced.

With this main object in view, the structure according to the invention includes a contact member resiliently supported by the conductor or conductors electrically connecting said member to the stationary terminal, a resilient abutment being provided so that the kinetic energy imparted to this contact member by the shock of the movable contact at the end of its circuit closing movement is absorbed simultaneously by the resilient conductors and by the resilient abutment.

Another object of the invention is to increase the contact pressure in the closed position of the circuit breaker without further means except these supporting conductors to urge magnetically the movable contact of the circuit breaker toward the stationary contact structure.

The invention will best be understood from a consideration of the following specification of a preferred embodiment thereof given by way of example, and referring to the accompanying drawings, in which:

FIG. 1 shows an elevational view of the pressure contacts according to the invention.

FIG. 2 represents a section along the line 11-11 of FIG. 1.

The circuit breaker to which the invention is applied comprises a movable contact 11 [and a stationary contact 20 which may be shaped as an arcing contact and which is so mounted on the insulator 22 by a bolt 23 that it can perform a limited movement in a direction parallel with the plane in which the movable contact moves. A rubber ring 21 is interposed between the insulator and the contact 20. The weight of the contact 20 is supported by the upper ends of the conductors 24 and 24', each of which is bent to form two turns covered by a layer of insulating material 16, 16'. The opposite ends of the conductors are rigidly connected respectively to the contact 20 and to the terminal 25 through the intermediary of a support member 26 having an opening 27 through which a U-shaped magnetic circuit 18 plate passes. The insulator 22 may be independent or may be solidly connected to the terminal 25 or to the insulator supporting the terminal. The stationary conductors 24, 24 are so designed, that their elasticity ensures a limited mobility to the contact member 20. As already known, the current flow in the winding formed by the conductors 24, 24 and the current fiow in the movable contact 11, in the closed position of this contact, develop clectrodynamic forces which urge the movable contact 11 toward the contact 20. The number of turns of the winding is chosen in accordance with the desired degree of closing pressure. The magnetic circuit 18 allows the concentration of a magnetic field in the useful part between the windings, where the arc is formed, and tends to displace the arc toward the arcing portions of the contact 11 and 201 carried by arm 12 and a stationary contact 20 formed of a mmallic block 13 held between jaws I4, 14' by rivets 15, 15 which may be shaped or an arcing contact and which is so mounted on the insulator 22 by a bolt 23 and nut 23 that it can perform a limited movement in a clirccliou parallel with the plane in which the movable COIIHIEI mover. A rubber ring 21 is interposed between the insulator and the contact 20. The weight of the contact is supported by the upper ends of the conductors 24 and 24', each of which is bent to form two turns covered by a layer of insulating material 16, 16'. Thc opposite ends of the conductors are rigidly couuecrcd rcspcctircly to the contact 20 by bolts l5, l5 and to the terminal 25 by bolts 19, 19', 19" through the intermediary of a rupport member 26 having on opening 27 through which a U-shapcd nmgnetic circuit 18 plate passes. The insulator 22 may be independent or may be solidly connected to the terminal 25 or to the insulafor supporting the terminal. The stationary conductors 24, 24' are so designed, that their elasticity ensures a limited mobility to the contact member 20. Ar alrcady known, the current flow in the winding formed by the conductors 24, 24' (indicated by arrow 31) and the current flow in the movable Contact 1] (indicated by arrow 30), in the closed position of this Contact, develop cloc- Irodynamic forces which urge the movable contact 11 toward the contact 20. The number 0 turns of the winding is chosen in accordance with the desired degree of closing pressure. The magnetic circuit 18 allows ihc couccntration of a magnetic field in the useful port between the windings, where the arc is formed, and tends to displace the arc toward the arcing portions of the Contact 11 and 20.

What is claimed is: [1. A shock absorbing contact for the movable contact arm of a circuit breaker comprising:

(a) a first fixed support (b) a contact bearing resiliently mounted on said first fixed support and axially reciprocable on said support (c) a second fixed support mounted below said first fixed support (d) resilient spring conductor means connected at one end to said fixed support and at the other end to said contact bearing and extending from said second fixed support to said contact bearing (c) said spring conductor means having its said other end rcciprocable with said contact bearing and its said one end stationary with respect to said second fixed support (I) said resilient conductor means including coil means positioned between the connected ends ol said spring conductor means (g) said coil means lying in a plane generally projected in the direction 01 travel of said movable contact arm] [2. A shock absorbing unit as in claim 1 and wherein:

(a) said coil means includes a first coil connected at one end to the right side of said contact hearing and connected at the other end to the right side of said second fixed support ([3) a second coil connected at one end to the left side of said contact hearing and connected at the other end to the left side of said second fixed support (c) said first and second coils being axially spaced from each other] [3. A shock absorbing unit as in claim 1 and including:

(a) a magnetic core mounted on said second fixed support and having arms extending laterally and alongside said coil means] 4. In (It) electrical circuit brcakcr of the type comprising a stationary contact mcmber tt'isplaccoln'y mounted on said circuit breaker, a movable contact member mounted on said circuit breaker for cooperation ll'lth suitl stationary contact mcmbcr, rcsilicnt spring conductor mcttns one end thereof being in fired relationship to said circuit breaker, mid stationary contact member being rcsilicntly .rupportcd on the othcr curl of said rcsilicnt conductor means, a shock absorbing device mountcd on said circuit brcukcr and disposed in spatial rclutionship to said stationary contact member to limit the displacement thereof in the dircction of motion of suit] movable contact member and to absorb the shock rcsulting from the closure of said contact members, the resilient spring conductor means bcing in such u spatial relationship with respect to said movable contact that in thc closed contact position repulsive clcctrodynomic forces are dcvclopcd which urge .sttid contacts together.

5. In it circuit breaker of the type (t.\ set forth and comprising the combination or act forth in claim 4, in which said resilient spring conductor Hlt'tllIA have the form of a coil having at lcust one convolution.

6. In a circuit breaker of the type us sct forth and comprising the combination as set forth in claim 4, said rcsilicnt spring means being bent in such it munlicr that, sccn in projection in a plttnc parallel to the motion of said movable contact mcmbcr, the projection of mid conductor means intersects twice the projection of the path of the electric current in said movulrlc contact mcm her.

7. In a circuit brcakcr of tltt type as set forth and comprising the combination (ZS sct forth in claim 4, mid rcsilicnt spring means bcing coiled to form a coil having or [cost a convolution in such a nuznncr thot, sccn in projcction in a plane porallcl to thc motion of sold movnblc contact mcmbcr, the projection of cnch convolution of Suit! coil intersects twice the proicctitm of the path of thc clcctric current in said movable contact mcmbcr.

8. In a circuit brcukcr of thc typc (and cti mprising the combination as set forth in claim 4, in which said rcsilicnt spring conductor means comprise two separate conductors mounted clcctrically in parallel and symmetrically disposed relatively to the plane of motion of said mov ublc contact member.

9. In a circuit breaker o the type and comprising the combination as set forth in claim 5, in which said rcsilicnt spring conductor means comprise two coilcd conductors, forming each a coil having at least one convolution, said coils being clcctricolly conncctcd in parallel and disposed symmetrically to the plane of motion of said movable contact member.

10. A shock absorbing contact for the movable contact arm of a circuit breaker comprising:

((1) a first fired support (b) a contact bearing rcsiliently mounted on said first fired support and axially reciprocal on said support (c) a second fixed support mounted below said first fixed support (d) resilient conductor means connected at one end to said fixed support and at the other end to said con tact bearing and extending from said second fixed support to said contact bearing (c) said conductor means having its other end reciprocal with said contact bearing and its said one end stationary with respect to said second fixed support (f) said resilient conductor means including coil means positioned between the connected ends of said spring conductor means g) said coil means lying in a plane generally pro jccted in the direction of travel of said movable contact arm.

1]. A shock absorbing contact as claimed in claim 10 in which:

((1') said coil means includes a first coil connccted at onc end to the right side of said contact bearing and connected at the other end to the right side of said second fixed support (b) a second coil conncctetl at one end to the left side of said contact bearing and connected at the other end to the left side of said second fixed support (c) said first and second coils being axially spaced from each other.

12. A shock absorbing contact as claimed in claim 10 and including a magnetic core mounted on said second fixed support and having arms extending laterally along the side of said coil means.

References Cited The following references, cited by the Examiner, are of record in the patented file of this patent or the original potent.

BERNARD A. GILHEANY, Primary Examiner.

R. I. ENVALL, JR., Assistant Examiner. 

